Archive of the former Yahoo!Groups mailing list: MOTM

While awaiting arrival of my MOTM modules, I've been meditating on
functional density in modular synthesizers. I've always operated on
a feeling about how much tonal richness I could get from a set of
modules, which had to do roughly with the quantity of activity going
on all at once. This is directly related to the number of distinct
signals available. The richness also has to do with the number of
voltage-controlled parameters that are being modulated
simultaneously.

I came up with a simple way to quantify the functional density of a
module as follows. It is the number of distinct signal sources
produced by a module plus the number of independently variable
voltage-controlled parameters afforded by the module, divided by the
panel width. Here's the breakdown for MOTM.

MOTM MODULE SOURCES PARAMS WIDTH DENSITY
-----------------------------------------------
101 S&H 2 0 2 1
120 SUB 0 0 2 0
190 VCA 0 2 1 2
300 VCO 1 2 2 1.5
310 VCO 1 2 1 3
320 LFO 1 2 2 1.5
380 LFO 4 0 1 4
390 LFO 2 1 1 3
410 VCF 2 3 2 2.5
410 VCF+OMS 2 6 3 2.66
420 VCF 0 1 2 0.5
440 VCF 0 2 2 1
480 VCF 0 2 2 1
490 VCF 0 1 1 1
700 ROUTER 0 2 2 1
800 EG 0 0 1 0
820 LAG 0 2 2 1
830 MIX 0 0 2 0
850 PEDAL 0 0 1 0
890 MIX 0 0 1 0

My rational for counting sources: The 101 S&H has one noise source,
plus one clock. Even though filters can oscillate, I'm not counting
that as a source. I don't count multiple waveforms coming from the
same oscillator.

Most of this is not too surprising. The quad LFO in a 1U panel has a
high functional density. Modules that do static processing, such as
envelope generators and mixers have zero density, which means that
when added to a system simply lower the overall density. To me that
gives them a lower value. But then I seem to be obsessed with
functional density!

This analysis did produce a few interesting results. The 310 micro
VCO has twice the functional density as its big brother, the 300,
because it has the same number of sources (1) and parameters (FM and
PWM), but in half the space. That's the idea, I suppose.

The 410 Triple Resonant Filter has a high functional density due to
the internal dual LFO, which adds two sources. The 410 also has
three independent parameters: combined filter frequency (sweep), LFO
rate, LFO internal modulation depth. Let's add the OMS-410. Now
there are six parameters: 3 independent filter frequency controls,
LFO rate, internal LFO depth, external LFO depth. This is based on
the MOTM-standard option panel for the OMS-410. But wait. Now it's
3U wide. Doing the math shows that adding the OMS-410 increased the
functional density only a tad from 2.5 to 2.66. But I like getting
those extra three parameters to control. Notice that this analysis
does not quantify the aspect of having the LFO outputs available
externally. Making the LFOs available for input to other processing
does not add any new sources to the system.

MY WISH LIST (Hey Paul!)

Being an old Serge guy, I long for the Serge dual slewing module.
Now, if Paul would make a very minor modification to the 820 Lag
Processor we would have this. Put a comparator with big hysteresis
on the output, so that when the output level reaches maximum (+5v)
the comparator puts out a -6v. Now the comparator will stay at -6v
until the output goes all the way down to -5v, at which point it
snaps back to +6v again. So what, you say? Well, now you now have a
pulse output. Patch that output into the lag input and now you have
an LFO with a voltage-controllable waveshape. Functional density
goes up to 1.5. But even better, I would like to see a micro Lag
Processor/LFO, fitting into a 1U panel with six jacks and three
pots.

Jacks: Input, Pulse Out, Lag Out, VC Up, VC Down, VC Up-Down
Pots: Initial Up, Initial Down, +/- Inverting attenuator VC Up-Down
input

Sources 1, Parameters 2, Width 1, Functional density 3.

I had about eight or so modules of different variants on this theme
in my original synthesizer (which is now probably gathering dust in
somebody's attic).

-Richard Brewster